The present invention relates generally to devices and methods for providing temporary placement of a filter in a blood vessel. More particularly, the invention provides a guidewire system for entrapment of embolic material in an artery or vein during an endovascular procedure. The system also provides a support wire for directing and/or exchanging other xe2x80x9cover the wirexe2x80x9d devices, such as angioplasty, atherectomy, or stent deployment catheters, to a region of interest within the vessel.
Treatment of thrombotic or atherosclerotic lesions in blood vessels using an endovascular approach has recently proven to be an effective and reliable alternative to surgical intervention in selected patients. For example, directional atherectomy and percutaneous translumenal coronary angioplasty (PTCA) with or without stent deployment are useful in treating patients with coronary occlusion. Atherectomy physically removes plaque by cutting, pulverizing, or shaving in atherosclerotic arteries using a catheter-deliverable endarterectomy device. Angioplasty enlarges the lumenal diameter of a stenotic vessel by exerting mechanical force on the vascular walls. In addition to using angioplasty, stenting, and/or atherectomy on the coronary vasculature, these endovascular techniques have also proven useful in treating other vascular lesions in, for example, carotid artery stenosis, peripheral arterial occlusive disease (especially the aorta, the iliac artery, and the femoral artery), renal artery stenosis caused by atherosclerosis or fibromuscular disease, superior vena cava syndrome, and occlusive iliac vein thrombosis resistant to thrombolysis.
It is well recognized that one of the complications associated with endovascular techniques is the dislodgment of embolic materials generated during manipulation of the vessel, thereby causing occlusion of the narrower vessels downstream and ischemia or infarct of the organ which the vessel supplies. In 1995, Waksman et al. disclosed that distal embolization is common after directional atherectomy in coronary arteries and saphenous vein grafts. See Waksman et al., American Heart Journal 129(3): 430-5 (1995), incorporated herein by reference. This study found that distal embolization occurs in 28% (31 out of 111) of the patients undergoing atherectomy. In January 1999, Jordan, Jr. et al. disclosed that treatment of carotid stenosis using percutaneous angioplasty with stenting is associated with more than eight times the rate of nicroemboli seen using carotid endarterectomy. See Jordan, Jr, et al. Cardiovascular surgery 7(1): 33-8 (1999), incorporated herein by reference.
Microemboli, as detected by transcranial Doppler monitoring in this study, have been shown to be a potential cause of stroke. The embolic materials include calcium, intimal debris, atheromatous plaque, thrombi, and/or air.
There are a number of devices designed to provide blood filtering for entrapment of vascular emboli. The vast majority of these devices are designed for permanent placement in veins to prevent pulmonary embolism. A temporary venous filter device is disclosed in Bajaj, U.S. Pat. No. 5,053,008 (this and all other references cited herein are expressly incorporated by reference as if fully set forth in their entirety herein). The Bajaj device is an intracardiac catheter for temporary placement in the pulmonary trunk of a patient predisposed to pulmonary embolism due to, e.g., hip surgery, major trauma, major abdominal or pelvic surgery, or immobilization. The Bajaj device includes an umbrella made from meshwork which traps venous emboli before they reach the lungs. This device is designed for venous filtration and is not suitable for arterial use because of the hemodynamic differences between arteries and veins.
There are very few intravascular devices designed for arterial use. Arteries are much more flexible and elastic than veins and, in the arteries, blood flow is pulsatile with large pressure variations between systolic and diastolic flow. These pressure variations cause the artery walls to expand and contract. Blood flow rates in the arteries vary from about 1 to about 5 L/min. Ginsburg, U.S. Pat. No. 4,873,978, discloses an arterial filtering system, which includes a catheter with a strainer device at its distal end. This device is inserted into the vessel downstream from the treatment site and, after treatment, the strainer is collapsed around the entrapped emboli and removed from the body. The Ginsburg device could not withstand flow rates of 5 L/min. It is designed for only small arteries and therefore could not capture emboli destined for all parts of the body. Ing. Walter Hengst GmbH and Co, German Patent DE 34 17 738, also discloses another arterial filter having a folding linkage system which converts the filter from the collapsed to the expanded state.
Filters mounted to the distal end of guidewires have been proposed for intravascular blood filtration. A majority of these devices includes a filter which is attached to a guidewire and is mechanically actuated via struts or a pre-shaped basket which deploys in the vessel. These filters are typically mesh xe2x80x9cparachutesxe2x80x9d which are attached to the shaft of the wire at the distal end and to wire struts which extend outward in a radial direction at their proximal end. The radial struts open the proximal end of the filter to the wall of the vessel. Blood flowing through the vessel is forced through the mesh thereby capturing embolic material in the filter. These devices are self-directing and can be placed intravascularly. However, one major disadvantage associated with the current devices is that the steerability of the guidewire may be altered as compared to the conventional guidewires due to the size of the filter. The guidewire may bend, kink, and/or loop around in the vessel, making insertion of the filter through a complex vascular lesion difficult.
During endovascular procedures, it is not uncommon to exchange one endovascular device for another over the guidewire. However, the guidewire position is often lost or compromised during the exchange of devices. For example, during coronary revascularization, it is often required to exchange of one guide catheter for another guide catheter possessing different qualities, e.g., a larger diameter guide to deliver a specialized angioplasty device, a smaller diameter guide to prevent deep intubation and/or pressure damping, a different guide shape, or a guide catheter containing side holes. It is known that there are few interventional maneuvers as challenging as attempting to maintain distal guidewire access while trying to exchange one guiding catheter for another without compromising the guidewire position.
What is needed are simple and safe blood filtering and guidewire systems which can be temporarily placed in the arteries and veins to prevent distal embolization during endovascular procedures, and can be used to introduce and/or exchange various instruments to a region of interest without compromising the position of the filter or guidewire. Existing devices are inadequate for this purpose.
The present invention provides devices and methods for introduction of endovascular devices, e.g., guide catheters, atherectomy catheters, angioplasty catheters, intravascular ultrasound catheters, or stent-deployment catheters, and for protecting a patient from distal embolization during cardiovascular procedures. More specifically, a guided filter system with support wire is disclosed for capturing embolic material generated during the procedure and for directing or exchanging other devices to a region of interest in an artery or vein.
In one embodiment, the filter system comprises a guidewire and a support wire having an expandable filter, e.g., a parachute, basket, or scroll, mounted on a distal region of the support wire. The support wire is adapted for percutaneous insertion into an artery or vein and is adapted to receive an endovascular instrument. The distal region of the support wire includes a wire guide, which slideably engages the guidewire. In certain embodiments, the wire guide comprises a ring having an aperture adapted to receive the guidewire.
In another embodiment, the filter comprises an expansion frame and a mesh disposed over the frame. The filter can be placed in a collapsed condition to facilitate entry into a vessel and an enlarged condition to capture embolic material in the vessel. In certain embodiments, the frame comprises a plurality of struts bonded to the guidewire at a first end, and the struts expand radially outward at a second end. The construction and use of expansion means and associated filter mesh have been thoroughly discussed in earlier applications including Barbut et al., U.S. application Ser. No. 08/533,137, filed Nov. 7, 1995, Barbut et al., U.S. application Ser. No. 08/580,223, filed Dec. 28, 1995, Barbut et al., U.S. application Ser. No. 08/584,759, filed Jan. 9, 1996, Barbut et al., U.S. application Ser. No. 08/640,015, filed Apr. 30 1996, Barbut et al., U.S. application Ser. No. 08/645,762, filed May 14, 1996, and Barbut et al., U.S. Pat. No. 5,662,671, and the contents of each of these prior applications are expressly incorporated herein by reference.
The methods of the present invention include deployment of a percutaneous medical instrument during an endovascular procedure to remove plaque and/or thrombi from the coronary artery, aorta, common carotid artery, external and internal carotid arteries, brachiocephalic trunk, middle cerebral artery, basilar artery, subclavian artery, brachial artery, axillary artery, iliac artery, renal artery, femoral artery, popliteal artery, celiac artery, superior mesenteric artery, inferior mesenteric artery, anterior tibial artery, posterior tibial artery, and all other arteries carrying oxygenated blood. The methods also include prevention of distal embolization during an endovascular procedure to remove thrombi and/or foreign bodies in the venous circulation, including the superior vena cava, inferior vena cava, external and internal jugular veins, brachiocephalic vein, pulmonary artery, subclavian vein, brachial vein, axillary vein, iliac vein, renal vein, femoral vein, profunda femoris vein, great saphenous vein, portal vein, splenic vein, hepatic vein, and azygous vein.
In a first method of using the guided filter system, the distal end of the guidewire is inserted percutaneously through an artery or vein and advanced into or beyond a region of interest, typically a stenotic lesion caused by buildup of atherosclerotic plaque and/or thrombi. In a collapsed condition, the filter and the distal region of the support wire are advanced over the guidewire, having the wire guide of the support wire engaging the guidewire, i.e., like a monorail catheter engaging a guidewire. The filter is expanded downstream of the vascular occlusion, and the guidewire is withdrawn and removed from the body. The distal region of an endovascular device, such as an atherectomy, stent-deployment, or angioplasty catheter, is inserted over the support wire and advanced to the region of interest. After the stenotic lesion is removed or otherwise treated by the endovascular device and an adequate lumenal diameter is established, the filter is collapsed and removed, together with the captured embolic debris, from the vessel by withdrawing the support wire.
In another method, after the guidewire and the support wire with the expanded filter are positioned in a vessel distal to the region of interest, the endovascular device is inserted over both the guidewire and the support wire to position within the region of interest. During certain cardiovascular procedures, especially coronary revascularization, exchange of endovascular instruments and catheters is needed and is difficult to accomplish because the initial guidewire positioning across the region of interest is often lost as the first device is withdrawn. Using the guided filter system, the guidewire and the support wire are both advanced distal to the region of interest. If the position of the guidewire is lost during the withdrawal of the first device, the second device that needs to be exchanged can be advanced over the support wire to be positioned within the region of interest.
It will be understood that there are several advantages in using the devices and methods disclosed herein for capturing and removing embolic debris during endovascular procedures. For example, the guided filter system (1) is particularly well suited for temporary filtration of blood in any vessel to entrap embolic debris, thereby minimizing neurologic, cognitive, and cardiac complications associated with distal embolization, (2) can withstand high arterial blood flow for an extended time, (3) includes a mesh that is sufficiently porous to allow adequate blood flow in a blood vessel while capturing emboli, (4) can be used to direct an endovascular catheter to a region of interest in the vessel, (5) can be used to exchange medical instruments without compromising the position of the guidewire, and (6) can be used in adult and pediatric patients.